The"X是X"construction echoes speaker's part of discourse"X"with certain linguistic means to ex-press the concession and affirmative discourse position,and the interpretation of its overall meaning cannot be ob-tained by adding up the meanings of its constituent components,therefore,it is called echo construction.From the perspective of the composition of the construction,the first"X"in the"X是X"construction is the echo component introduced by the speaker B from the speaker A's speech."是"plays a role of repeating or copying,together with the latter"X",expressing the subjective evaluation of speaker B on speaker A's"X".It has the semantic feature of concession affirmation and the semantic feature of echo affirmation.The"X是X"construction is widely used at the beginning of the responses in dialogues with a strong interactive function,and in monologue with explicit and implicit interaction.